/* ========== 基础与变量 ========== */
:root {
  --bg: #060a16;
  --bg-alt: #0a1122;
  --bg-card: rgba(148, 178, 255, 0.05);
  --line: rgba(148, 178, 255, 0.14);
  --text: #e8eefc;
  --muted: #93a1c0;
  --cyan: #22d3ee;
  --blue: #3b82f6;
  --grad: linear-gradient(120deg, #22d3ee, #3b82f6 60%, #6366f1);
  --radius: 18px;
  --font: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", "Source Han Sans SC", -apple-system, "Segoe UI", sans-serif;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}
body::before {
  content: "";
  position: fixed; inset: 0;
  background:
    radial-gradient(60% 45% at 85% -5%, rgba(59, 130, 246, 0.13), transparent 65%),
    radial-gradient(50% 40% at 0% 20%, rgba(34, 211, 238, 0.08), transparent 60%);
  pointer-events: none; z-index: 0;
}
img, svg { display: block; }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
.container { width: min(1180px, 92%); margin: 0 auto; position: relative; z-index: 1; }
::selection { background: rgba(34, 211, 238, 0.35); }

/* ========== 加载动画 ========== */
.preloader {
  position: fixed; inset: 0; z-index: 100;
  background: var(--bg);
  display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 26px;
  transition: opacity .6s ease, visibility .6s;
}
.preloader.done { opacity: 0; visibility: hidden; }
.preloader__logo { display: flex; flex-direction: column; align-items: center; gap: 14px; font-size: 20px; font-weight: 700; letter-spacing: .35em; text-indent: .35em; animation: pl-pulse 1.6s ease-in-out infinite; }
@keyframes pl-pulse { 50% { opacity: .55; } }
.preloader__bar { width: 180px; height: 3px; border-radius: 3px; background: rgba(148,178,255,.15); overflow: hidden; }
.preloader__bar i { display: block; height: 100%; width: 40%; background: var(--grad); border-radius: 3px; animation: pl-slide 1.1s ease-in-out infinite; }
@keyframes pl-slide { 0% { transform: translateX(-100%);} 100% { transform: translateX(350%);} }

/* ========== 导航 ========== */
.header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 50;
  padding: 18px 0;
  transition: background .35s, padding .35s, box-shadow .35s;
}
.header.scrolled {
  padding: 10px 0;
  background: rgba(6, 10, 22, 0.82);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  box-shadow: 0 1px 0 var(--line);
}
.header__inner { display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.brand { display: flex; align-items: center; gap: 12px; }
.brand__text { display: flex; flex-direction: column; line-height: 1.25; }
.brand__text strong { font-size: 19px; letter-spacing: .06em; }
.brand__text small { font-size: 10px; letter-spacing: .28em; color: var(--muted); }
.nav { display: flex; align-items: center; gap: 34px; font-size: 15px; }
.nav a { position: relative; color: var(--muted); transition: color .25s; padding: 6px 0; }
.nav a::after {
  content: ""; position: absolute; left: 0; bottom: 0; height: 2px; width: 0;
  background: var(--grad); border-radius: 2px; transition: width .3s;
}
.nav a:hover, .nav a.active { color: var(--text); }
.nav a:hover::after, .nav a.active::after { width: 100%; }
.nav__cta {
  color: var(--text) !important;
  border: 1px solid rgba(34, 211, 238, 0.5);
  padding: 8px 20px !important; border-radius: 999px;
  transition: background .25s, box-shadow .25s !important;
}
.nav__cta::after { display: none; }
.nav__cta:hover { background: rgba(34, 211, 238, 0.12); box-shadow: 0 0 24px rgba(34, 211, 238, 0.25); }
.nav-toggle { display: none; background: none; border: 0; cursor: pointer; padding: 8px; z-index: 60; }
.nav-toggle span { display: block; width: 24px; height: 2px; background: var(--text); margin: 5px 0; border-radius: 2px; transition: transform .3s, opacity .3s; }
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ========== 首屏 ========== */
.hero {
  position: relative; min-height: 100svh;
  display: flex; align-items: center;
  padding: 130px 0 90px;
  overflow: hidden;
}
.hero__canvas { position: absolute; inset: 0; width: 100%; height: 100%; }
.hero__glow { position: absolute; border-radius: 50%; filter: blur(90px); pointer-events: none; }
.hero__glow--a { width: 520px; height: 520px; top: -140px; right: -80px; background: rgba(59, 130, 246, 0.22); animation: float 9s ease-in-out infinite; }
.hero__glow--b { width: 420px; height: 420px; bottom: -160px; left: -100px; background: rgba(34, 211, 238, 0.14); animation: float 11s ease-in-out infinite reverse; }
@keyframes float { 50% { transform: translateY(-34px); } }
.hero__inner { max-width: 860px; }
.hero__eyebrow {
  font-size: 13px; letter-spacing: .42em; color: var(--cyan);
  margin-bottom: 22px; font-weight: 600;
}
.hero__title {
  font-size: clamp(40px, 6.6vw, 76px);
  line-height: 1.18; font-weight: 800; letter-spacing: .02em;
  margin-bottom: 26px;
}
.hero__title span { display: block; }
.hero__title .grad {
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
}
.hero__sub { font-size: clamp(15px, 1.6vw, 18px); color: var(--muted); max-width: 640px; margin-bottom: 38px; }
.hero__sub strong { color: var(--text); }
.hero__actions { display: flex; flex-wrap: wrap; gap: 16px; margin-bottom: 44px; }
.btn {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 14px 30px; border-radius: 999px;
  font-size: 16px; font-weight: 600; cursor: pointer;
  border: 0; transition: transform .25s, box-shadow .25s, background .25s, border-color .25s;
}
.btn--primary {
  background: var(--grad); color: #04101f;
  box-shadow: 0 10px 34px rgba(34, 211, 238, 0.3);
}
.btn--primary:hover { transform: translateY(-3px); box-shadow: 0 16px 44px rgba(59, 130, 246, 0.45); }
.btn--primary svg { transition: transform .25s; }
.btn--primary:hover svg { transform: translateX(4px); }
.btn--ghost { border: 1px solid var(--line); color: var(--text); background: rgba(148, 178, 255, 0.04); }
.btn--ghost:hover { border-color: rgba(34, 211, 238, 0.55); background: rgba(34, 211, 238, 0.08); transform: translateY(-3px); }
.btn--block { width: 100%; justify-content: center; }
.hero__badges { display: flex; flex-wrap: wrap; gap: 26px; color: var(--muted); font-size: 14px; }
.hero__badges span { display: inline-flex; align-items: center; gap: 9px; }
.dot { width: 8px; height: 8px; border-radius: 50%; background: var(--grad); box-shadow: 0 0 12px rgba(34, 211, 238, 0.8); }
.hero__scroll {
  position: absolute; left: 50%; bottom: 26px; transform: translateX(-50%);
  width: 26px; height: 44px; border: 2px solid rgba(148, 178, 255, 0.35); border-radius: 14px;
  display: flex; justify-content: center; padding-top: 8px; z-index: 2;
}
.hero__scroll span { width: 4px; height: 9px; border-radius: 4px; background: var(--cyan); animation: scroll-hint 1.8s ease-in-out infinite; }
@keyframes scroll-hint { 0% { transform: translateY(0); opacity: 1; } 70% { transform: translateY(14px); opacity: 0; } 100% { opacity: 0; } }

/* ========== 数据条 ========== */
.stats { padding: 20px 0 60px; }
.stats__grid {
  display: grid; grid-template-columns: repeat(5, 1fr); gap: 16px;
  background: var(--bg-card); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 34px 30px;
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
}
.stat { text-align: center; }
.stat b {
  display: block; font-size: clamp(26px, 3.4vw, 40px); font-weight: 800;
  background: var(--grad); -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
  line-height: 1.2; margin-bottom: 6px;
}
/* 用直接子级选择器：原 `.stat span:last-child` 会连带命中数字内部的 .count（<b> 的最后一个元素子级），
   把大号数字压成 13.5px 灰色，导致「数字小、单位大」的反向层级 */
.stat > span:last-child { color: var(--muted); font-size: 13.5px; }
/* 单位/角标：随数字等比缩放（em），与数字同基线、同渐变填充 */
.stat__unit { font-size: .5em; font-weight: 600; letter-spacing: .01em; }

/* ========== 通用区块 ========== */
.section { padding: 110px 0; position: relative; }
.section--alt { background: linear-gradient(180deg, rgba(10, 17, 34, 0.65), rgba(10, 17, 34, 0.25) 55%, transparent); }
.section__head { text-align: center; max-width: 720px; margin: 0 auto 64px; }
.section__tag { font-size: 12.5px; letter-spacing: .4em; color: var(--cyan); font-weight: 700; margin-bottom: 14px; }
.section__head h2 { font-size: clamp(28px, 4vw, 42px); font-weight: 800; letter-spacing: .02em; }
.section__desc { color: var(--muted); margin-top: 14px; }

/* ========== 关于我们 ========== */
.about__grid { display: grid; grid-template-columns: 1.15fr .85fr; gap: 56px; align-items: start; }
.about__text p { color: var(--muted); margin-bottom: 18px; }
.about__text strong { color: var(--text); }
.about__points { margin-top: 30px; display: grid; gap: 14px; }
.about__points li {
  position: relative; padding: 16px 20px 16px 64px;
  background: var(--bg-card); border: 1px solid var(--line); border-radius: 14px;
  color: var(--muted); font-size: 15px; transition: border-color .3s, transform .3s;
}
.about__points li:hover { border-color: rgba(34, 211, 238, 0.4); transform: translateX(6px); }
.about__points b {
  position: absolute; left: 16px; top: 50%; transform: translateY(-50%);
  width: 38px; height: 38px; border-radius: 11px;
  background: rgba(34, 211, 238, 0.12); color: var(--cyan);
  display: flex; align-items: center; justify-content: center; font-size: 14px;
}
.about__panel { position: relative; }
.panel-card {
  background: linear-gradient(160deg, rgba(34, 211, 238, 0.09), rgba(59, 130, 246, 0.05) 45%, rgba(148, 178, 255, 0.04));
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 34px 32px; position: relative; z-index: 1;
  backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
}
.panel-card h3 { font-size: 20px; margin-bottom: 20px; }
.panel-card dl { display: grid; gap: 14px; }
.panel-card dl > div { display: grid; grid-template-columns: 74px 1fr; gap: 14px; font-size: 14px; }
.panel-card dt { color: var(--cyan); font-weight: 600; white-space: nowrap; }
.panel-card dd { color: var(--muted); }
.panel-orbit { position: absolute; inset: -30px; z-index: 0; pointer-events: none; }
.panel-orbit i {
  position: absolute; border-radius: 50%; border: 1px dashed rgba(34, 211, 238, 0.22);
  animation: orbit-spin 16s linear infinite;
}
.panel-orbit i:nth-child(1) { width: 120px; height: 120px; top: -20px; right: 6%; }
.panel-orbit i:nth-child(2) { width: 70px; height: 70px; bottom: 4%; left: -8px; animation-duration: 11s; animation-direction: reverse; }
.panel-orbit i:nth-child(3) { width: 40px; height: 40px; top: 40%; right: -14px; animation-duration: 8s; }
@keyframes orbit-spin { to { transform: rotate(360deg); } }

/* ========== 服务项目 ========== */
.services__grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.svc {
  position: relative; overflow: hidden;
  background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 34px 30px 30px;
  transition: transform .35s, border-color .35s, box-shadow .35s;
}
.svc::before {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(420px 200px at var(--mx, 50%) var(--my, 0%), rgba(34, 211, 238, 0.1), transparent 65%);
  opacity: 0; transition: opacity .35s; pointer-events: none;
}
.svc:hover { transform: translateY(-8px); border-color: rgba(34, 211, 238, 0.45); box-shadow: 0 22px 50px rgba(2, 8, 23, 0.55); }
.svc:hover::before { opacity: 1; }
.svc__icon {
  width: 58px; height: 58px; border-radius: 16px;
  background: rgba(34, 211, 238, 0.1); color: var(--cyan);
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 22px; transition: transform .35s, background .35s;
}
.svc__icon svg { width: 28px; height: 28px; }
.svc:hover .svc__icon { transform: scale(1.08) rotate(-4deg); background: rgba(59, 130, 246, 0.18); }
.svc h3 { font-size: 20px; margin-bottom: 12px; }
.svc p { color: var(--muted); font-size: 14.5px; margin-bottom: 16px; }
.svc ul { display: grid; gap: 8px; }
.svc ul li { position: relative; padding-left: 18px; font-size: 13.5px; color: var(--muted); }
.svc ul li::before { content: ""; position: absolute; left: 0; top: 9px; width: 7px; height: 7px; border-radius: 2px; background: var(--grad); }
.svc__no {
  position: absolute; top: 20px; right: 24px;
  font-size: 44px; font-weight: 800; line-height: 1;
  color: transparent; -webkit-text-stroke: 1px rgba(148, 178, 255, 0.22);
}

/* ========== 服务流程 ========== */
.timeline { display: grid; grid-template-columns: repeat(5, 1fr); gap: 18px; counter-reset: step; position: relative; }
.timeline::before {
  content: ""; position: absolute; top: 34px; left: 5%; right: 5%; height: 1px;
  background: linear-gradient(90deg, transparent, rgba(34, 211, 238, 0.4), rgba(59, 130, 246, 0.4), transparent);
}
.timeline__item { position: relative; text-align: center; padding: 0 8px; }
.timeline__no {
  display: flex; align-items: center; justify-content: center;
  width: 68px; height: 68px; margin: 0 auto 20px;
  border-radius: 50%; font-weight: 800; font-size: 19px;
  background: var(--bg-alt); border: 1px solid rgba(34, 211, 238, 0.45); color: var(--cyan);
  box-shadow: 0 0 0 8px rgba(34, 211, 238, 0.05);
  position: relative; z-index: 1; transition: transform .3s, box-shadow .3s;
}
.timeline__item:hover .timeline__no { transform: scale(1.1); box-shadow: 0 0 0 10px rgba(34, 211, 238, 0.1), 0 0 30px rgba(34, 211, 238, 0.35); }
.timeline__item h3 { font-size: 18px; margin-bottom: 10px; }
.timeline__item p { color: var(--muted); font-size: 13.5px; }

/* ========== 核心优势 ========== */
.strengths__grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.strength {
  background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 32px 30px; transition: transform .35s, border-color .35s;
}
.strength:hover { transform: translateY(-6px); border-color: rgba(59, 130, 246, 0.5); }
.strength h3 { display: flex; align-items: center; gap: 14px; font-size: 18px; margin-bottom: 14px; }
.strength__key {
  flex: none; width: 46px; height: 46px; border-radius: 13px;
  background: var(--grad); color: #04101f;
  display: flex; align-items: center; justify-content: center;
  font-size: 22px; font-weight: 800;
  box-shadow: 0 8px 22px rgba(34, 211, 238, 0.28);
}
.strength p { color: var(--muted); font-size: 14.5px; }

/* ========== 服务行业 ========== */
.industries__grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.ind {
  text-align: center; padding: 36px 24px;
  background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius);
  transition: transform .35s, border-color .35s, background .35s;
}
.ind:hover { transform: translateY(-6px); border-color: rgba(34, 211, 238, 0.45); background: rgba(34, 211, 238, 0.06); }
.ind__icon { display: flex; justify-content: center; margin-bottom: 16px; }
.ind__icon img { width: 76px; height: 76px; transition: transform .35s; }
.ind:hover .ind__icon img { transform: scale(1.07) translateY(-2px); }
.ind h3 { font-size: 18px; margin-bottom: 8px; }
.ind p { color: var(--muted); font-size: 13.5px; }

/* ========== 服务区域 ========== */
.areas__grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.area {
  padding: 30px 26px;
  background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius);
  transition: transform .35s, border-color .35s, background .35s;
}
.area:hover { transform: translateY(-6px); border-color: rgba(34, 211, 238, 0.45); background: rgba(34, 211, 238, 0.06); }
.area h3 { font-size: 17px; margin-bottom: 10px; }
.area h3::before {
  content: ""; display: inline-block; width: 7px; height: 7px; border-radius: 50%;
  background: var(--grad); margin-right: 10px; vertical-align: middle;
}
.area p { color: var(--muted); font-size: 14px; line-height: 1.85; }

/* ========== 常见问题 ========== */
.faq__list { max-width: 900px; margin: 0 auto; display: grid; gap: 12px; }
.faq {
  background: var(--bg-card); border: 1px solid var(--line); border-radius: 14px;
  overflow: hidden; transition: border-color .3s, background .3s;
}
.faq[open] { border-color: rgba(34, 211, 238, 0.38); background: rgba(34, 211, 238, 0.05); }
.faq summary {
  position: relative; cursor: pointer; list-style: none;
  padding: 18px 54px 18px 22px; font-size: 16px; font-weight: 600; color: var(--text);
  transition: color .25s;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary:hover { color: var(--cyan); }
.faq summary::after {
  content: "+"; position: absolute; right: 22px; top: 50%; transform: translateY(-50%);
  color: var(--cyan); font-size: 22px; font-weight: 400; line-height: 1;
  transition: transform .25s;
}
.faq[open] summary::after { transform: translateY(-50%) rotate(45deg); }
.faq p { color: var(--muted); font-size: 14.5px; padding: 0 22px 20px; }

/* ========== 跑马灯 ========== */
.marquee { overflow: hidden; padding: 26px 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); background: rgba(10, 17, 34, 0.5); }
.marquee__track { display: flex; gap: 54px; width: max-content; animation: marquee 26s linear infinite; }
.marquee__track span {
  font-size: 17px; font-weight: 700; letter-spacing: .18em; white-space: nowrap;
  color: transparent; -webkit-text-stroke: 1px rgba(148, 178, 255, 0.4);
  transition: color .3s;
}
.marquee__track span:hover { color: var(--cyan); -webkit-text-stroke-color: transparent; }
@keyframes marquee { to { transform: translateX(-50%); } }

/* ========== 联系我们 ========== */
.contact__grid { display: grid; grid-template-columns: .9fr 1.1fr; gap: 52px; align-items: start; }
.contact__item { padding: 22px 0; border-bottom: 1px dashed var(--line); }
.contact__item:first-child { padding-top: 0; }
.contact__label {
  display: inline-block; font-size: 12px; letter-spacing: .3em; color: var(--cyan);
  font-weight: 700; margin-bottom: 8px;
}
.contact__item p { color: var(--muted); font-size: 15px; }
.contact__qr { display: flex; align-items: center; gap: 18px; margin-top: 26px; }
.contact__qr-box {
  width: 112px; height: 112px; border-radius: 16px; flex: none;
  border: 1px dashed rgba(34, 211, 238, 0.5); color: var(--cyan);
  display: flex; align-items: center; justify-content: center;
  background: rgba(34, 211, 238, 0.05);
}
.contact__qr-box--img {
  border: 1px solid rgba(34, 211, 238, 0.35);
  border-radius: 0;
  background: #f2f8ff; overflow: hidden; padding: 0;
  box-shadow: 0 10px 34px rgba(34, 211, 238, 0.16);
  transition: transform .3s, box-shadow .3s;
}
.contact__qr-box--img:hover { transform: scale(1.04); box-shadow: 0 14px 44px rgba(34, 211, 238, 0.28); }
.contact__qr-box--img img { width: 100%; height: 100%; object-fit: cover; display: block; }
.contact__qr p { color: var(--muted); font-size: 13px; }
.contact__form {
  background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 36px 34px; display: grid; gap: 18px;
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
}
.form__row { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.contact__form label { display: grid; gap: 8px; font-size: 14px; color: var(--muted); }
.contact__form input, .contact__form select, .contact__form textarea {
  font-family: inherit; font-size: 15px; color: var(--text);
  background: rgba(6, 10, 22, 0.6); border: 1px solid var(--line);
  border-radius: 12px; padding: 13px 16px; outline: none; resize: vertical;
  transition: border-color .25s, box-shadow .25s;
}
.contact__form input:focus, .contact__form select:focus, .contact__form textarea:focus {
  border-color: rgba(34, 211, 238, 0.6); box-shadow: 0 0 0 4px rgba(34, 211, 238, 0.1);
}
.contact__form input::placeholder, .contact__form textarea::placeholder { color: rgba(147, 161, 192, 0.55); }
.contact__form select { appearance: none; background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%), linear-gradient(135deg, var(--muted) 50%, transparent 50%); background-position: calc(100% - 21px) 50%, calc(100% - 15px) 50%; background-size: 6px 6px; background-repeat: no-repeat; }
.contact__form select option { background: var(--bg-alt); color: var(--text); }
.form__tip { font-size: 14px; min-height: 22px; text-align: center; }
.form__tip.ok { color: #34d399; }
.form__tip.err { color: #f87171; }

/* ========== 页脚 ========== */
.footer { border-top: 1px solid var(--line); background: rgba(6, 10, 22, 0.85); position: relative; z-index: 1; }
.footer__inner {
  display: grid; grid-template-columns: 1.4fr 1fr 1fr 1.2fr; gap: 40px;
  padding: 64px 0 44px;
}
.footer__brand p { color: var(--muted); font-size: 14px; margin-top: 16px; }
.footer__col h4 { font-size: 15px; margin-bottom: 16px; color: var(--text); }
.footer__col a { display: block; color: var(--muted); font-size: 14px; padding: 5px 0; transition: color .25s, transform .25s; }
.footer__col a:hover { color: var(--cyan); transform: translateX(4px); }
.footer__col p { color: var(--muted); font-size: 14px; }
.footer__bottom { border-top: 1px solid var(--line); padding: 20px 0; }
.footer__bottom .container { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px; }
.footer__bottom p { color: rgba(147, 161, 192, 0.7); font-size: 13px; }

/* ========== 回到顶部 ========== */
.backtop {
  position: fixed; right: 26px; bottom: 26px; z-index: 40;
  width: 48px; height: 48px; border-radius: 50%;
  background: var(--bg-alt); border: 1px solid var(--line); color: var(--cyan);
  cursor: pointer; display: flex; align-items: center; justify-content: center;
  opacity: 0; visibility: hidden; transform: translateY(14px);
  transition: opacity .3s, transform .3s, visibility .3s, border-color .3s, box-shadow .3s;
}
.backtop.show { opacity: 1; visibility: visible; transform: translateY(0); }
.backtop:hover { border-color: rgba(34, 211, 238, 0.6); box-shadow: 0 0 24px rgba(34, 211, 238, 0.3); }

/* ========== 滚动显现动画 ========== */
.reveal { opacity: 0; transform: translateY(34px); transition: opacity .8s cubic-bezier(.22,.61,.36,1) var(--d, 0s), transform .8s cubic-bezier(.22,.61,.36,1) var(--d, 0s); }
.reveal.visible { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  .marquee__track, .panel-orbit i, .hero__glow, .preloader__bar i, .preloader__logo { animation: none; }
  html { scroll-behavior: auto; }
}

/* ========== 响应式 ========== */
@media (max-width: 1024px) {
  .services__grid, .strengths__grid, .industries__grid, .areas__grid { grid-template-columns: repeat(2, 1fr); }
  .timeline { grid-template-columns: repeat(2, 1fr); gap: 34px 18px; }
  .timeline::before { display: none; }
  .stats__grid { grid-template-columns: repeat(3, 1fr); row-gap: 28px; }
  .about__grid, .contact__grid { grid-template-columns: 1fr; gap: 44px; }
  .footer__inner { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 680px) {
  .section { padding: 76px 0; }
  .nav {
    position: fixed; inset: 0; z-index: 55;
    flex-direction: column; justify-content: center; gap: 30px;
    background: rgba(6, 10, 22, 0.96); backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px);
    font-size: 20px;
    opacity: 0; visibility: hidden; transition: opacity .35s, visibility .35s;
  }
  .nav.open { opacity: 1; visibility: visible; }
  .nav-toggle { display: block; }
  .services__grid, .strengths__grid, .industries__grid, .areas__grid, .timeline, .form__row { grid-template-columns: 1fr; }
  .stats__grid { grid-template-columns: repeat(2, 1fr); padding: 26px 18px; }
  .hero { padding-top: 110px; }
  .hero__actions .btn { width: 100%; justify-content: center; }
  .footer__inner { grid-template-columns: 1fr; gap: 30px; padding: 48px 0 34px; }
  .contact__form { padding: 26px 20px; }
  .backtop { right: 16px; bottom: 16px; }
}